Tracking SARS-CoV-2 in the city of Houston’s wastewater system Presented by: Loren Hopkins, PhD Chief Environmental Science Officer Bureau Chief Community and Children's Environmental Health Houston Health Department Tuesday, Sep 2nd, 2020 Today’s Agenda 3 ▪ ▪ ▪ ▪ ▪ Team Introduction Methodology Analysis of results Comparison between wastewater and clinical-based positivity rates ▪ Conclusions Collaborative Team Houston Health Department: Loren Hopkins, PhD, Lilian Mojica, MS, Braulio Garcia, Daniel Bahrt, Courtney Hundley, MPH, Jeremy Rangel, Ruochen Liu, MS Houston Water – Wastewater Operations: Carol LaBreche, PE, Walid Samarneh, PE, Paul Zappi, PE, Rae Mills, PE Rice University: Lauren Stadler, PhD, Kathy Ensor, PhD, Phil Bedient, PhD, Roberto Bertolusso, PhD, Prashant Kalvapalle, Zach LaTurner TAILOR Molecular Virology and Microbiology, Baylor College of Medicine: Anthony Maresso, PhD, Tony Piedra, MD, Viasanthi Avadhanula, PhD, Austen Terwilliger, PhD, Justin Clark, PhD, Haroldo de Santos Hernandez Today’s Agenda 5 ▪ ▪ ▪ ▪ ▪ Team Introduction Methodology Analysis of results Comparison between wastewater and clinical-based positivity rates ▪ Conclusions What is wastewater surveillance? 6 ▪ Infected persons (asymptomatic and symptomatic) shed the virus in feces ▪ Feces enters the sewage network ▪ Wastewater collected at the treatment plant is an aggregate or pooled sample ▪ Results o o Qualitative (positive or negative) Quantitative (viral genomes/L wastewater) Advantages of Wastewater Monitoring ▪ Can serve as an early warning system for outbreaks ▪ Detects resurgence in communities ▪ Less expensive mass surveys ▪ Coverage in areas with little clinical testing information ▪ Can be used to identify geographic areas of concern Today’s Agenda 8 ▪ ▪ ▪ ▪ ▪ Team Introduction Methodology Analysis of results Comparison between wastewater and clinical-based positivity rates ▪ Conclusions Monitoring 39 Sewersheds Across Houston ▪ 39 wastewater treatment plants o o 2.1 million people 670 square miles ▪ Once per week ▪ 24-hour composite samples of influent Monitoring Manholes and Lift Stations 11 ▪ Sensitive locations: o ▪ Congregant living centers New locations will be monitored in October: o o Long-term care facilities Segmenting large areas Quantification Methods 12 24 hr. composite samples of influent from wastewater treatment plants/manholes/lift stations Concentration of virus using adsorption to filters Extraction and purification of viral genomes Quantification of viral genomes Today’s Agenda 13 ▪ ▪ ▪ ▪ ▪ Team Introduction Methodology Analysis of results Comparison between wastewater and clinical-based positivity rates ▪ Conclusions Statistical analysis Data collected every week: ▪ Two laboratories (Rice and BCM) ▪ Results from triplicate samples ▪ Two different primers N1 and N2 (12 readings total) ▪ Exact flow rates from each WWTP ▪ Population (manholes) 14 Overall Trend 15 Individual WWTP Trend 16 Virus load trend direction: 8/17 to 8/24 Virus load trend direction: 8/24 to 8/31 Virus load trend direction: 8/31 to 9/07 Examples of use of WWTP trend at zip code cluster 20 Examples of use of WWTP trend at zip code cluster 21 Recent: 1,800 Active: 473 Locations jittered to de-identify Examples of use of WWTP trend at zip code cluster 22 Recent: 156 Active: 28 Locations jittered to de-identify ZIP code 77036 23 Segmenting large areas: Soon HHD will be sub-sampling three lift stations within the same zip code. Locations jittered to de-identify Today’s Agenda 24 ▪ ▪ ▪ ▪ ▪ Team Introduction Methodology Analysis of results Comparison between wastewater and clinical-based positivity rates ▪ Conclusions WWTP comparison to clinical positivity rates 25 27 Today’s Agenda 28 ▪ ▪ ▪ ▪ ▪ Team Introduction Methodology Analysis of results Comparison between wastewater and clinical-based positivity rates ▪ Conclusions 24-hour composite influent samples are collected from 39 wastewater treatment plants each week Health Department uses wastewater data to inform interventions, including additional testing Samples are transported to a central laboratory facility and aliquoted into bottles. SARS-CoV-2 in quantified in replicate samples in two independent laboratories. Raw data is input into statistical models that identify geographic areas of concern with significant increases in wastewater virus concentration. Conclusions 30 ▪ Complements positivity rate to monitor COVID-19 in our communities ▪ Serves to better target and direct interventions ▪ Future uses: estimation of prevalence, granular monitoring at schools Questions?